Battery charging system



F. BENEDICT BATTERY CHARGING SYSTEM Flled March 3, 1952 March 24, 1936.

INVENTOR BY y/t/mu f/g l I Patented Mar. 24, 1936 UNITED STATES PATENTOFFICE BATTERY CHARGING SYSTEM Application March 3, 1932, Serial No.596,553

11 Claims.

.. 28s to battery charging sys- -..-cu.-. lly to a system for conofbatteries according to the c marged condition thereof.

When certain types of batteries such as storage batteries used forrailway signalling purposes are trickl charged it has been found that itis very diflicult to regulate the charging rate in such a manner thatthe battery is constantly maintained in a fully charged condition. Thedifiiculty expericnced in maintaining such a charging rate is due to theload on the battery being variable and often after a constant chargingrate is established the battery may at times be greatly over- 5 chargedand at other times it may be undercharged. 7

It has been found impractical to either control the charging of abattery or to regulate its charging rate by taking advantage ofvariations in as terminal voltage of such battery, because suchvariations are slight between a. maximum charged condition and a.practically discharged condition. However there is a much morepronounced change in the charging current of such battery 25 from themaximum charging current at a discharged condition of the battery to aminimum current at a fully charged condition thereof.

It is therefore proposed in accordance with this invention to provide ameans which will interrupt the charging circuit of a battery when thecurrent in its charging circuit falls below a predetermined value. It isobvious that when the charging circuit is thus interrupted, an externalmeans must be provided for again starting the charging operation of thebattery, and it is also proposed in accordance with this invention toprovide in the automatic battery charging control system an automaticmeans for periodically restoring the charging circuit.

Ether objects, purposes and characteristic feathe invention will appearas the description thereof progresses during which reference will bemade to the accompanying drawing which shows the invention in a mannerto make it easily 45 understood rather than with the view of showing theparticular arrangement preferably employed in practice. and in which:-

Fig. 1 diagrammatically shows a system for controlling the charging of abattery associated 50 with a railway track circuit as one application ofthe present invention, and

Fig. 2 is a modified arrangement of the present invention applied in amanner similar to Fig. 1.

Referring to Fig. l of the accompanying draw- 55 ing a portion ofrailway track T is shown divided into two track sections by theinsulated joints I. Across the rails at one end of these sections isconnected 2. track battery B of the conventional storage type. Acrossthe rails at the other end of these sections is connected 3. track relayTR, 5 which may be the same relay as used in the conventional blocksignalling systems. A source of battery charging energy is indicated bythe conventional arrangement of a. full wave rectifier R connected to atransformer TF which is in turn connected to an alternating currentsource of energy AC.

The control of the battery charging is effected in Fig. 1 by adifferential relay 0, which is indicated as comprising two coils P andC. The coil P may be termed the battery potential coil, which it can beseen is connected directly across the terminals of the battery B andconsequently the windings of this coil P will be of comparatively highresistance. The coil C is a series charging current coil and is arrangedso that during anormal charging rate, or a rate at which the battery ischarge when not in a fully charged condition, the tractive force ofthese coils is approximately equal, but, as shown, the magnetic effectsof these coils P and C are opposed to each other, and consequently inthis condition substantially no resultant tractive force will act on thearmature of this relay.

The circuit for charging the battery B may be traced from the positiveoutput terminal of the rectifier R, wires 2 and 3, back contact l of thedifferential control relay 0, wires 4, 5 and 6, through the battery B,wires '1, 8 and Q, through the current coil C of the control relay 0,and back to the negative side of the rectifier R by wire it]. In as muchas the battery voltage may be considered to be approximate constantvariations in the tractive force of the armature of this relay will beprincipally effected by the variation in the charging current due to thechange in the charged condition of the battery '13. When the battery Bbecomes fully charged it is obvious that a smaller current will flowthrough the series winding C, and consequently its effect will notequalize the tractive force produced by the potential winding P, whichlatter winding will then pick up the armature of the relay and open thecharging circuit at back contact i.

It is now obvious that this charging circuit will remain openindefinitely unless it can be again established by an external shuntaround open back contact I of relay 0. A method of supplying the shuntmay be obtained in several man- 55 ners such as a back contact ll of atrack relay, as shown, a contact of a signal mechanism, a midstrokecontact of a switch machine mechanism, or any contact which isperiodically made. If a track relay be used, as shown, it is normallyenergized as by a source such as B, connected across the rails at theopposite end of its block, whereby occupancy of the block causes the carwheels and axles to shunt the relay and cause it to release its contactfinger.

The operation of this shunt is to again set up a charging circuit which,owing through the series coil may or may not be OPSufficient value toequalize the effect of the potential winding P depending upon thecharged condition of the battery B. However if suificient energy hasbeen taken from the battery B, between the time of interruption of thecharging circuit by the differential relay and the establishing of thiscircuit by the dropping of the track relay TR, the current in the newlyestablished charging circuit will be of a value which will sufficientlynearly equalize the effect of the potential Winding P to cause thearmature of the relay to remain down, and contact 5 will thereafterremain closed until the battery has been again sufficiently charged toreduce the charging current to a value effecting the picking up of therelay armature.

The modified arrangement shown in Fig. 2 of the accompanying dra ingwith like parts shown with distinctive e pon s is the same in itsoperation except that a s. gie coil relay 0 is substituted for thedieren ai relay 6 in Fig. i, and the battery charging circuit iscontrolled by a front contact i of this relay 9 instead of the backcontact of relay 0 in Fig. l. The relay 0 has its operating windi seri swith the charging circuit for b so arranged that the this circuit whenthe battery .s a ea is sufficient to hold up the armat the circuit atfront contact tery becomes fully charged this charging current decreasesto a value which will no longer effect the holding up s. the armature ofthe relay 0 thus opening the charging circuit at front contact i Thesame back contact of the track relay TR is shown as a means forrestoring the charg ing circuit and of course may be substituted by anyof the means outlined in connection with the arrangement shown in Fig.l. The operation of this restoring means is obvious, or that is, afterestablishing the charging circuit, the picking up of the tracls relayallows the charging of the to be controlled by the relay G [a batterycharging circuit has thus been provided which automaticaily cuts on thecharging,

current when the battery has been fully charged, as determined thearrangement of windings a differential relay or by a marginal seriesreand a means for periodically re-establishing the charging circuit thusinterrupted, which functions only to initiate the battery charging andsuch charging will continue only in the event that the battery is not ina fully charged condition.

In describing the present invention attention has been directed to thespecific embodiments thereof which were shown, without attempting topoint out the various alternate or optional features of construction, orthe diiTerent organizations and combinations that may be employed. Forexample the track relay shown as a means However when the battery, asource of charging current for said battery, a relay having one windingenergized by the potential of said battery and a second windingoppositely connected relative thereto and in series with a circuitincluding a contact of said relay and charging said battery from saidsource of current whereby said relay picks up its armature when thecurrent charging said battery falls bu low a predetermined value.

2. In a battery charging system, a storage battery, a source of chargingcurrent for said battery and a relay having one winding ener gized bythe potential of said battery and second winding oppositely connectedrelative thereto and in series with a circuit for charging said batteryincluding a back contact of said relay whereby said charging current isinterrupted by the picking up of said relay when the current chargingsaid battery falls below a predetermined value.

3. In a battery charging system, a storage battery, a source of chargingcurrent for said battery, a relay having one winding energized by thepotential of said battery and a second winding oppositely connectedrelative thereto and in series with a circuit for charging said batteryincluding a back: contact of said relay whereby said charging current isinterrupted by the picking up of said relay when the current chargingsaid battery falls below a predetermined value, and means arranged tointermittently establish said circuit for charging said battery.

4. A battery charging system comprising a storage battery, a source ofcharging current, a (inferential relay having a potential winding and aseries charging current winding, contact means operated by said relayarranged to prevent the charging of said battery when the effect of thepotential winding of said relay is greater than the effect of saidseries charging current winding and an initiating means arranged tointermittently start the charging of said battery.

5. In a railway track circuit, an insulated track section, a batterysupplying current to the rails of said track section, a source of energyfor charging said battery, a dilierentialrelay, a circult for chargingsaid battery including a series winding and a back contact of saiddifferential relay, a potential winding on said diiferential re layconnected to said battery so as to oppose said series winding wherebysaid differential relay is picked up when the current in said chargingcircuit falls below a predetermined value and means arranged to startthe charging of said battery in accordance with. railway trafiic.

5. In a railway signalling system, a storagebattery, means for supplyingcharging current for said battery, a differential relay having a batterypotential winding and a series charging current winding, contact meansoperated by said relay arranged to prevent charging said battery whenthe effect of the battery potential winding is greater than the efiectof said series winding and means restoring said charging circuit by achange in condition of a traffic controlled device.

7. A battery charging system including a battery, a charging source ofenergy, a difierential relay having a battery potential winding con--nected across the battery and a series charging winding connected in acharging circuit and means controlled by the relay for preventingcharging when the effect of the potential winding is greater than theeffect of the series winding.

8. In a battery charging system, a storage battery, means for supplyingcurrent capable of charging said battery, a relay having its operatingwindings and a front contact thereof in series with a circuit forcharging said battery whereby charging of said battery is interruptedwhen the charging current falls below a predetermined value, and meansfor establishing said charging circuit in a manner to energize saidrelay.

9. In a system for charging a railway track circuit battery, a storagetrack battery, a source of energy capable of charging said battery, arelay having a winding connected in series with a circuit for chargingsaid battery, contact means operated by said relay and arranged tointerrupt said charging circuit when the current in said relay windingfalls below a predetermined value, and a track relay having a backcontact operable to re-establish said charging circuit.

10. In combination, a first source of energy, a two-element relayarranged to attract its armature when energized with the normalpotential of said first source of energy but to release its armaturewhen the potential of said first source of energy falls below apredetermined value, a second source of energy, and means connectingsaid second source of energy in multiple with said first source ofenergy through one element of said two-element relay when the armatureof said two-element relay is released whereby the efiect of one elementof said two-element relay opposes the effect of the other element.

11. In a supply system, in combination, a load, a normal source ofenergy for normally supplying the load, an auxiliary source of energynormally disconnected from the load, a relay having differentialwindings and normally energized by the normal source to attractedposition, a circuit connecting the auxiliary source to the load andincluding a back point of the relay and one of the windings of the relayto offset the effect of the normal source on the relay.

FRANK BENEDICT.

